The present invention generally relates to a cutting papers machine for cutting into pieces such as those documents to be discarded of or disposed and, more particularly, to a shredding machine.
There has been known a shredding mechanism provided with a pair of cutting rollers oppositely rotating with respect to each other, and a shredding mechanism provided with a rotary cutter and a fixed cutter combined with the rotary cutter. The latter is disclosed in, for example, Japanese Utility Model Publication No. 51-45585. According to the Japanese Utility Model, the mechanism includes the rotary cutter having spiral edges and the fixed cutter arranged to contact with the edges of the rotary cutter under pressure. The rotary cutter has plural spiral edges and is rotatably supported by bearings through column parts of which are formed at both ends of the rotary cutter and have the outer diameters smaller than the outer diameters of the edges thereof. The fixed cutter is supported by a supporting member to contact with the rotary cutter under pressure by a spring. The rotary cutter is so constructed that the column parts and a cutter part with the spiral edges are separately manufactured and then are assembled to each other to form one rotary cutter.
Since according to the conventional mechanism, the cutter part of the rotary cutter must be manufactured separately from the column parts as holding parts for rotatably holding the rotary cutter, it results in complicated construction and lower productivity. Since the cutter part is separated from the column parts, each section at which the cutter part is connected with each of the column parts often suffers some damage when applying any force to the section. The requirement of holding means for holding both ends of the column parts of the rotary cutter in the arrangement causes the holding means to become complicated in construction.
Furthermore, in the conventional machine, the papers transporting direction in which paper such as those documents to be discarded or disposed of are fed into the machine is not shown. The shredding capability of the mechanism depends on the direction of feed in a shredding machine with the mechanism constructed by a combination of between the fixed cutter and the rotary cutter. For example, when the papers are fed in the same direction as a direction in which the rotary cutter moves rotates, the direction for shredding the papers is the same as the direction for feeding the papers, thereby causing shredding capability to decrease or a shredding operation to be impossible.
Moreover, in the conventional shredding mechanism, the rotary cutter contacts with the fixed cutter under pressure and rotation of the rotary cutter causes sheets of the papers to cut into pieces. In this case, almost the same hardness of the cutters by a hardening process results in heat evolution by friction therebetween in rotation of the rotary cutter, occurrence of a metal sound by partial contact therebetween based on any error in manufacturing and assembling, and an insufficient shredding operation. For preventing these disadvantageous, various kinds of members including the cutters and the holding means for holding the cutters must be manufactured and assembled with high accuracy to result in higher manufacturing and assembling cost and very troublesome assemblage.